/Engine/Source/Runtime/Engine/Classes/Materials/MaterialExpressionPathTracingBufferTexture.h
Path tracing buffer is only accessable in postprocess material.
class UMaterialExpressionPathTracingBufferTexture : public [UMaterialExpression](API\Runtime\Engine\Materials\UMaterialExpression)
FExpressionInpu...
Coordinates
UV in 0..1 range
TEnumAsByte< EP...
PathTracingBufferTextureId
Which path tracing buffer texture we want to make a lookup into.